You have the older green gears which makes them no newer than 2012 or 2013 so they definitely can have some miles on them - they don't owe you anything at this point, but should work fine from what I can see in the photo
. The newer blue gears are tougher but those green ones are quite respectable.
The planetary bearings are always sloppy, they really don't carry much load and just vaguely keep the gears spaced apart in orbit around the sun gear. The frozen bearing is not good though and you may be able to free it up or pop in a new one if you are handy. These tiny bearings are virtually impossible to remove from the clutch assembly without damage since there's no good means to access the inner race and prying them off by the gear+outer race is an invitation to damage. So - leave the gears mounted up unless you are going to replace them for sure.
Anyhow - on to the problem at hand - I'm wondering if you were fiddling with the phase wires prior to this incident because what you describe is exactly what happens when the motor runs backwards. All you hear is a quiet ZZZZing sound as the motor spins in reverse preventing the clutch from engaging. Interchanging two phase wires could cause this as could shorting FWD/REV controller wires if you have them.
FWIW - BMC parts are fantastically expensive and pretty rare these days but the entire clutch/gear assembly from a MAC or eZee will fit as a direct replacement. Over the years there have been minor variations in the thickness of the gears and clutches in the BMC/Mac/eZee lines so you typically don't want to mix parts - even within brand. However, the overall outer dimensions are the same, so replace the whole assembly if you go that route. The gray Mac gears are quite tough - I use Mac parts in one of my BMCs - they're inexpensive, too ($55 from EM3EV). I have some notes on the gears in my Yuba build thread and there are several other related posts on ES as well.